Ok further to the last, I think it;s a mapdata.xml issue WRT what bmp is activated. Still investigating as it should be a yellow h2s mao. bmp at all levels?
This is very frustrating!

I have tried in 3 different installs but end up not only with the green screen but also all the airbases which shouldn't show up! AFAIK, that bmp is not even present in the installs!
dlgingamebriefmap
<Dialog Image="help/h2s_screen.bmp" Movable="No" ZOrder="Top" Offset="10,10">
<Button ID="Cancel" X="6" Y="6" Width="50" Height="50" NoCaption="Yes" Image="common_screens/overlay.bmp"/>
<Label ID="ctrl6" Caption="" X="520" Y="21" Width="80" Height="14" FontName="metaltype" Align="Center"/>
<EditBox ID="edtDescription" X="517" Y="51" Width="247" Height="441" ReadOnly="true" Image="common_screens/dropbox.bmp[1]" FontName="textfontflt" Textcolor="#000000,#000000,#000000"/>
<MissionMap ID="map" X="6" Y="6" Width="500" Height="500" Image="ctrl"/>
</Dialog>
mapdata ( but I removed the icons.)
<!--This file describes what images should be used for displaying the Campaign/Waypoints map-->
<MapData>
<Maps>
<!-- Alt specifies the minimal altitude (in meters) starting from which the given map image should be displayed. -->
<Level Alt="500000.0">
<Map Image="map\h2s.bmp">
<UpperLeft Lat="N45 29 39.5581" Lon="E9 21 50.2722"/>
<LowerRight Lat="N28 30 20.4946" Lon="E30 38 9.6909"/>
</Map>
</Level>
<Level Alt="200000.0">
<Map Image="map\h2s.bmp">
<UpperLeft Lat="N45 29 39.5581" Lon="E9 21 50.2722"/>
<LowerRight Lat="N28 30 20.4946" Lon="E30 38 9.6909"/>
</Map>
</Level>
<Level Alt="0.0">
<Map Image="map\h2s.bmp">
<UpperLeft Lat="N45 29 39.5581" Lon="E9 21 50.2722"/>
<LowerRight Lat="N28 30 20.4946" Lon="E30 38 9.6909"/>
</Map>
</Level>
</Maps>
<Icons>
<Icon Type="airbase1" Image="common_screens\airbase_blue.bmp[2]" Alt="0."/>
<Icon Type="airbase2" Image="common_screens\airbase_red.bmp[2]" Alt="0."/>
<Icon Type="airbase_empty" Image="common_screens\airbase_gray.bmp[2]" Alt="0."/>
<Icon Type="bridge1" Image="common_screens\bridge_blue.bmp[2]" Alt="1000000."/>
<Icon Type="bridge2" Image="common_screens\bridge_red.bmp[2]" Alt="1000000."/>
<Icon Type="factory1" Image="common_screens\factory_blue.bmp[2]" Alt="1000000."/>
<Icon Type="factory2" Image="common_screens\factory_red.bmp[2]" Alt="1000000."/>
<Icon Type="railyard1" Image="common_screens\railyard_blue.bmp[2]" Alt="1000000."/>
<Icon Type="railyard2" Image="common_screens\railyard_red.bmp[2]" Alt="1000000."/>
<Icon Type="port1" Image="common_screens\port_blue.bmp[2]" Alt="1000000."/>
<Icon Type="port2" Image="common_screens\port_red.bmp[2]" Alt="1000000."/>
<Icon Type="hq1" Image="campaign\map_btnBlue.bmp[2]" Alt="0."/>
<Icon Type="hq2" Image="campaign\map_btnRed.bmp[2]" Alt="0."/>
<Icon Type="hq_human" Image="campaign\map_btnGrn.bmp[2]" Alt="0."/>
<Icon Type="hq_plrnat" Image="campaign\map_btnYel.bmp[2]" Alt="0."/>
<Icon Type="trgsec" Image="campaign\map_TargRed.bmp[1]" Alt="0."/>
</Icons>
</MapData>